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991.
992.
A coordination polymer {[Co(N3)2(dps)2]·0.5H2O}n (1) (dps=dipyridin-4-ylsulfane) with one dimensional chains has been synthesized and the structure and magnetic properties were characterized. Complex 1 crystallizes belongs to monoclinic system and has space group P21/c. The CoⅡ ion is six-coordinated and located at a compressed octahedral environment due to the Jahn-Teller effect. The ligand of dps bridges between CoⅡ ions producing the infinite chains of Co…Co along a direction and, interestingly, four pyridyl groups of dps ligands form a propeller-shaped coordination geometry around CoⅡ ion with the same spiral within the chain. These 1D chains are further linked through the hydrogen bonds to generate a 3D supermolecular network. Magnetic studies indicated that complex 1 shows very weak antiferromagnetic coupling between CoⅡ ions in low temperature. CCDC: 769596. 相似文献
993.
Tetrahydrofuran (THF) hydrate was formed in bulk as well as in glass beads pack with a mean diameter of 3.0 mm by controlling the temperature under ambient pressure. Images of THF hydrate formation procedure were obtained using the magnetic resonance imaging (MRI) technique. The experiment results showed that MRI is an effective method for the detection of hydrate formation. Saturation of hydrate formed both in bulk and glass beads can be confirmed by intensity integration of MRI images. 相似文献
994.
995.
996.
Sarkar M Aromí G Cano J Bertolasi V Ray D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(46):13825-13833
A high-spin Co(II) cluster with a rare pentagonal molecular structure and formula [Co(5)(CO(3))(2)(bpp)(5)]ClO(4) (1; Hbpp is 2,6-bis(phenyliminomethyl)-4-methylphenolate) has been synthesized and characterized by single-crystal X-ray diffraction. This topology arises from fusing five [Co(2)(bpp)] moieties in a cyclic manner around two CO(3)(2-) central ligands, resulting in propeller-like configuration. The irregular coordination of the carbonate ions to the metal centers results in a combination of coordination numbers (CNs) of the Co(II) ions of five and six. The bulk magnetization of this complicated magnetically exchanged system has been modeled successfully by employing a matrix diagonalization technique. For this, the combination of S=3/2 ions (CN=5) with ions exhibiting strong spin-orbit coupling (CN=6) has been considered and a perturbative approach to handle the data in the whole studied range of temperatures (2-300 K) yielding parameters of g and D (for the five-coordinate Co(II) ions), of A, κ, λ, and Δ (for the metals with spin-orbit coupling) and of the exchange constants J. The agreement with results from DFT calculations, also presented here, is remarkable. 相似文献
997.
Junli Wang Dr. Qing Yang Prof. Zude Zhang Shouheng Sun Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(26):7916-7924
Transition‐metal phosphide nanowires were facilely synthesized by Ullmann‐type reactions between transition metals and triphenylphosphine in vacuum‐sealed tubes at 350–400 °C. The phase (stoichiometry) of the phosphide products is controllable by tuning the metal/PPh3 molar ratio and concentration, reaction temperature and time, and heating rate. Six classes of iron, cobalt, and nickel phosphide (Fe2P, FeP, Co2P, CoP, Ni2P, and NiP2) nanostructures were prepared to demonstrate the general applicability of this new method. The resulting phosphide nanostructures exhibit interesting phase‐ and composition‐dependent magnetic properties, and magnetic measurements suggested that the Co2P nanowires with anti‐PbCl2 structure show a ferromagnetic–paramagnetic transition at 6 K, while the MnP‐structured CoP nanowires are paramagnetic with Curie–Weiss behavior. Moreover, GC‐MS analyses of organic byproducts of the reaction revealed that thermally generated phenyl radicals promoted the formation of transition‐metal phosphides under synthetic conditions. Our work offers a general method for preparing one‐dimensional nanoscale transition‐metal phosphides that are promising for magnetic and electronic applications. 相似文献
998.
Dr. Fabrice Pointillart Dr. Thomas Cauchy Dr. Olivier Maury Yann Le Gal Dr. Stéphane Golhen Dr. Olivier Cador Dr. Lahcène Ouahab 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(39):11926-11941
The tetrathiafulvalene‐amido‐2‐pyridine‐N‐oxide ( L ) ligand has been employed to coordinate 4f elements. The architecture of the complexes mainly depends on the ionic radii of the lanthanides. Thus, the reaction of L in the same experimental protocol leads to three different molecular structure series. Binuclear [Ln2(hfac)5(O2CPhCl)( L )3] ? 2 H2O (hfac?=1,1,1,5,5,5‐hexafluoroacetylacetonate anion, O2CPhCl?=3‐chlorobenzoate anion) and mononuclear [Ln(hfac)3( L )2] complexes were obtained by using rare‐earth ions with either large (LnIII=Pr, Gd) or small (LnIII=Y, Yb) ionic radius, respectively, whereas the use of TbIII that possesses an intermediate ionic radius led to the formation of a binuclear complex of formula [Tb2(hfac)4(O2CPhCl)2( L )2]. Antiferromagnetic interactions have been observed in the three dinuclear compounds by using an extended empirical method. Photophysical properties of the coordination complexes have been studied by solid‐state absorption spectroscopy, whereas time‐dependent density functional theory (TD‐DFT) calculations have been carried out on the diamagnetic YIII derivative to build a molecular orbital diagram and to reproduce the absorption spectrum. For the [Yb(hfac)3( L )2] complex, the excitation at 19 600 cm?1 of the HOMO→LUMO+1/LUMO+2 charge‐transfer transition induces both line‐shape emissions in the near‐IR spectral range assigned to the 2F5/2→2F7/2 (9860 cm?1) ytterbium‐centered transition and a residual charge‐transfer emission around 13 150 cm?1. An efficient antenna effect that proceeds through energy transfer from the singlet excited state of the tetrathiafulvalene‐amido‐2‐pyridine‐N‐oxide chromophore is evidence of the YbIII sensitization. 相似文献
999.
Commercially available linear alkylbenzenesulfonates (LASs) are a mixture of various homologues and isomers, leading to 20 major species. In this work we investigated the commercial product by liquid chromatography-solid phase extraction-nuclear magnetic resonance spectroscopy-mass spectrometry (LC-SPE-NMR/MS). The commercial product was separated into 17 fractions by liquid chromatography (LC). After chromatographic separation, 5% of the flow was split to a mass spectrometer (MS) while 95% was send to post-column solid phase extraction cartridges for enrichment of the analytes (LC-SPE). After elution from the SPE-cartridges a NMR-spectrometer equipped with a cryo-probe was used for the characterisation of the different LASs species. For the first time 1H-1D and H-H-COSY spectra for 14 LASs species out of 20 major isomers are presented, whereas the 6 remaining species are detected as mixtures in 3 1H-1D and H-H-COSY spectra. These data were used to correlate the chromatographic retention of the LASs isomers to the substitution pattern of the alkyl chain. 相似文献
1000.
Dalva E. C. Ferreira Wagner B. De Almeida Ademir Neves Willian R. Rocha 《International journal of quantum chemistry》2010,110(5):1048-1055
Density functional theory (DFT) calculations with different exchange‐correlation functionals were performed for a mixed valence Fe(II)/Fe(III) binuclear complex with μ‐methoxo and two μ‐carboxylate bridging ligands, (1) with geometry optimizations being performed for all possible spin multiplicities (MS = 2, 4, 6, 8, and 10). Within the exchange‐correlation functionals studied, only the hybrid GGA functionals B3P and B3LYP and also the pure GGA functional RPBE, predicts the geometry with high spin (S = 9/2) to be more stable than the geometry with low spin state (S = 1/2) by 20 kcal/mol, in agreement with the experimental findings. These functionals also predict the same stability order for the different spin states, being MS = 10>8>6>2>4. The meta‐GGA functionals TPSS and TPSSh and also the pure GGA functionals BLYP and BP86 predict different stability orders. The computed average EPR g‐tensor, gav, of 2.03, at the B3LYP level, is in good agreement with the experimental findings. Heisenberg exchange coupling constants, J, were calculated within the broken‐symmetry formalism, at the B3LYP level, showing that the two iron centers are antiferromagnetic coupling, with a very weak coupling constant of about ?7 cm?1, in good agreement with the experimental value. Additionally, the effect of using different multiplicities of the reference geometries on the computed J value is discussed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献